Experiments are now in progress to determine if the dolichyl phosphate phosphatase which we found in Tetrahymena pyriformis plays a role in controlling the levels of dolichyl phosphate and thereby the rate of glycoprotein biosynthesis, or if this enzyme is a relatively non-specific phosphatase which happens to hydrolyze this compound. Experiments are also being conducted to isolate and at least partially purify the dolichol esterase which we have recently found. Again the aim of these studies is an attempt to relate the activities of these enzymes with the concentration of dolichol phosphate in the cell, which all the experimental evidence to date indicates is a controlling factor in the formation of glycolated intermediates for the control of glycoprotein synthesis. We are also concluding studies on the polyprenol composition of Tetrahymena pyriformis with the hope that increased knowledge of the dolichol composition of this organism may permit us to exploit this easily manipulated system to study dolichol metabolism.